Frailty and myosteatosis are each prognostic of all-cause mortality (ACM) in patients with cancer. However, it is unclear whether myosteatosis adds value to frailty for predicting ACM. We assessed whether myosteatosis improves the predictive ability of frailty for ACM in older adults undergoing chemotherapy. This was a retrospective study of older adults (≥65 years) initiating chemotherapy between June 2015 and June 2022. Frailty was assessed using a 24-item frailty index (FI). Myosteatosis was evaluated via computed tomography scans at the third lumbar vertebra (L3).. Multivariable Cox regression and Uno's c-statistic determined the predictive performance of the FI and myosteatosis. In total, 115 participants (mean age: 77.1 years) were included. Frailty alone (adjusted hazards ratio (aHR) = 1.68, 95% confidence intervals (CIs) = 1.03-2.72, p = 0.037) and myosteatosis alone (aHR = 2.14, 95%CI = 1.07-4.30, p = 0.032) exhibited similar performance (c-statistic = 0.66) in predicting ACM in multivariable analyses adjusted for age, sex, body mass index, and treatment intent. However, the highest predictive performance for ACM was observed after inclusion of both myosteatosis and frailty in the multivariable model (c-statistic = 0.70). Myosteatosis improves the performance of frailty for predicting ACM in older adults with cancer. Prospective studies to assess the effect of exercise on myosteatosis in older patients are warranted.
Keywords: cancer; frailty; muscle density; myosteatosis; older adults; survival.